Questions And Answers

All people entering the manufacturing area are required to wear the"blue" coats. I was told they are anti-static, but I doubt that they provide more control than preventing the generation of a static charge. Your catalogue says they are dissipative. If so, where does the charge dissipate to, and how? In its article on "smocks", the website says they are a Faraday Cage. If that is so, how does it work? Is it by containing the charge inside the coat (the conductor), outside the coat, around a conductive layer, or what? Does it work if the coat is unbuttoned or if any clothing is exposed? For example, would there be any protection of trousers that extend beyond the coat? What objective measurements are available that show they are effective? - Anonymous, Croydon, Australia

Answer

The material of our smocks is in fact dissipative. There is a conductive fiber woven within the fabric connecting all the panels together. In addition, there is a patented conductive strip that is stitched inside the smock to provide hands free use while grounding the garment. In order for the garment to work properly, you need to ground it. This may be accomplished in 3 ways: (1) wear a wrist strap and attach the snap to the smock at the sleeve (there is a 4mm socket built into our smocks on each sleeve for this purpose). Then attach a coil cord to the hip snap of the hip-to-cuff connection of the smock to ground. (2) use our smocks with stretch cuffs that have a conductive material built into the cuff, bypassing the need of a separate wrist strap. You only need to attach the grounded coil cord to the hip snap. (3) or, if you are standing on an ESD conductive floor, wear foot grounders or ESD shoes to complete the path to ground of the smock with either a wrist strap attached to or elastic conductive cuff of the smock. The smock only works when it is completely covering the street or work clothes underneath. If the street clothing were exposed at the sleeve or chest (because it wasn’t buttoned up) then the electric fields of the insulative clothing can produce stray electric fields within your ESD Safe area. You can show that a smock is effective by using a field meter and measuring a charged person before and after donning a grounded smock. The effectiveness of the smock is contained only to the smocks area of coverage, i.e., will not protect exposed pants, slacks or stockings. Generally, these types of clothing are more than 12 inches from ESD sensitive materials. Also, you can quantify your ESD control program before and then after introducing smocks into it by comparing the value of the scrap product produced from quality problems.